The silk is from the Bombyx mori silk worm, often referred to as "mulberry" silk. 5 yards About Treenway Silks’ Ribbons--All widths of Treenway Silk's ribbons are woven with selvage edges. The selvage edge can hold up to stitching on fabric or being pulled through a large-count canvas.--The silk used is the highest quality reeled silk which still has the sericin in it. The sericin acts as a natural sizing. --The warp (length-wise) threads are two strands of fine silk which are twisted together. There are 300 fine warp threads per inch. --The weft (cross-wise threads) is a single silk strand. --The ribbon is woven in plain weave, where the weft thread goes over and under each individual warp thread, all the way across the ribbon, giving a strong, stable ribbon. Hand-dyed in Colorado--color fast. We use acid dyes with heat and then rinse until water runs clear.Wash in tepid or slightly warm water.